The present invention relates to closures or caps used to close containers. More particularly, this invention relates to an improved closure or cap for sealing a container aseptically filled with a liquid nutritional product, such as infant formula for example. Whether or not the container is equipped with a metal foil membrane seal hermetically covering the container opening, the present invention provides a linerless cap for sealing the container. Advantageously, the cap of this invention can be used to securely reseal a foil membrane sealed container after the membrane has been punctured. The need for a separate liner installed in the cap is eliminated.
Closures or caps are often utilized to close the mouth or opening of a container. It is sometimes desirable that these closures be capable of repeatedly sealing the container. Prior art closures have included the following features: a sealing member positioned inside the container opening, use of a separate foam liner, and an inflexible or permanently deformable sealing member. All of these features contain certain shortcomings.
Closures having a sealing member positioned inside the opening of a container are undesirable where a container has been initially closed with a membrane seal. The membrane-sealed container is usually shipped with a closure fastened over the membrane. In this case, a closure that seals the container through penetration within the opening of the container is impractical since it would interfere with or damage the membrane seal.
The rim about a container opening will typically have variations in its finish and/or height. When a metal foil membrane is attached in covering relation to the container rim additional variation can result. A separate foam liner installed in the cap is often required to overcome these problems. In this situation a liner is provided between the closure and the container where the closure is insufficient to effectively seal the container by itself. These liners are typically attached to the closure prior to the closure being fastened to the container. The use of a liner is undesirable since it requires increased manufacturing complexity and cost.
Further, an inflexible or permanently deformable sealing member will be unable to accommodate the uneven rim with repeated use. Closures having a sealing member that is inflexible or permanently deformable are unsatisfactory for accommodating manufacturing variations in containers. Closures that are inflexible or permanently deformable may be unable to tolerate finish variations, resulting in an imperfect or failed seal.
Therefore, a principal object of this invention is to provide a sealing closure capable of sealing a container without penetrating an opening in the container.
Another object of the invention is to provide a sealing closure that effectively eliminates the need for a liner to maintain a seal between a container and the sealing closure.
A further object of the invention is to provide a sealing closure capable of sealing a container while accommodating height, finish or other surface variations at the rim of the container.
These and other objects will be apparent to those skilled in the art.